JP3556261B2 - Surge arrester - Google Patents

Abstract

The surge arrester contains two connection armatures (1, 2) separated from each other along an axis, at least one cylindrically shaped varistor element (7) being arranged between them. The connection armatures (1, 2) and the one or more varistor element(s) (7) are braced together with the formation of a contact force to form a mechanically stable active part of the surge arrester. The active part is enclosed by a cast housing (12) made of insulating material. The active part is braced by at least two loops (5) acting independently of each other on the connection armatures (1, 2). The loops (5) are arranged with a separation from the one or more varistor element(s) (7). The connection armatures (1, 2) contain bearing surfaces, in each case corresponding to the number of loops (5) and azimuthally distributed regularly about the axis, one loop end being supported in each case on one of these bearing surfaces. In spite of simple design, the surge arrester exhibits good mechanical and electrical properties and can be produced in particularly cost-efficient ways. <IMAGE>

Description

[0001]
[Industrial applications]
The present invention provides two connecting members spaced apart from each other along an axis, at least one cylindrical varistor element disposed between the two connecting members, A device made of an insulating material for fastening and fixing the at least one varistor element under the formation of a contact force, and an insulating material surrounding the connecting member, the at least one varistor element and the fixing device at least partially Lightning arrester having a cast casing.
[0002]
[Prior art]
The invention relates to the known art, for example as described in EP-A-0 335 480. The lightning arrester according to the prior art includes a plurality of vertically stacked non-linear resistive elements having varistor characteristics arranged between two current connecting members. By means of windings made of a non-conductive material, which are guided around these parts of the resistance element and the connection element, the connection element and the resistance element are clamped under the force acting in the axial direction. This force is necessary to create a current path through which a large current must be introduced for a short time in the event of an overvoltage. A cast casing made of weather-resistant synthetic resin surrounds most of the resistance elements, windings and connecting members.
[0003]
The manufacture of this type of arrester is costly. The reason is that the resistance element is housed in the synthetic resin tube and the winding of the winding is relatively complicated.
[0004]
[Problems of the Invention]
It is an object of the present invention to provide a lightning arrester which has satisfactory mechanical and electrical properties in spite of its simple structure and can be manufactured in an advantageous manner in terms of extra costs.
[0005]
[Means for Solving the Problems]
This object is achieved according to the invention, starting from an arrester of the type mentioned at the outset, in the following manner. That is, the fixing device comprises a pressure screw and at least two fixing members, each acting independently of one another, on the connecting member and each being configured as a loop, the loop comprising two loop ends. The connecting members each include a bearing area corresponding to the number of the loops, the bearing areas being distributed azimuthally uniformly around the axis, wherein the bearing area has a shoulder shape Are arranged on at least one projection of the two connecting members, formed as parts, or in recesses formed as grooves, the respective bearing areas of the first connecting member of the two connecting members are: In a bearing area which is axially aligned with the bearing area of the second connecting element of the two connecting elements and which is aligned with the two connecting elements relative to one another Two loops end of the loop is supported.
[0006]
[Action]
The lightning arrester according to the invention is simpler to construct, despite its excellent mechanical and electrical properties, compared to comparable lightning arresters according to the prior art, and therefore can be manufactured particularly economically It is characterized by that. The assembly simply requires a mold that is pre-manufactured and temporarily guarantees axial guidance. In this form, a connecting element and at least one varistor element are first stacked and then connected to the mechanically stable active part of the lightning arrester by forming a loop and forming a biasing force. During the subsequent production of the cast casing, the active part can be injection molded very reliably without gaps and cavities. Therefore, the lightning arrester of the present invention has not only satisfactory mechanical characteristics but also good electrical characteristics.
[0007]
The loop can be pre-manufactured and then only needs to be further mounted in the bearing area of the connecting member during assembly. A particularly stable and yet small-sized loop comprises a band wound in a loop shape, which band is advantageously embedded in a synthetic resin substrate. The mechanical stability of the active part can then be achieved by subsequent fastening of the elements stacked in the mold during assembly, for example using a pressure screw provided on one of the two connecting members. it can. It can also be supplemented by a spring element which is incorporated into the elements stacked in the mold and which is biased during the mounting of the loop, based on the desired contact force and thus the required mechanical stability.
[0008]
If the loops are each formed of an elastically deformable strip of glass fiber, for example, additional clamping devices or additional spring elements can be omitted. The strip is then wrapped around the connecting member by means of the contact force and thus the biasing force which is pregiven by the contact force, based on the mechanical stability of the active part, and in this case each of the two connecting members Supported in each of the bearing areas.
[0009]
Advantageously, the wound strip may be embedded in a synthetic resin substrate formed by curing a curable synthetic resin after placing the loop in the bearing area. This strip is advantageously impregnated with a preheated synthetic resin, for example based on epoxides (prepreg), which is cured after winding, which is carried out on the basis of a biasing force. This type of strip has a good adhesive strength, so that if it is used, a fastening device for the strip end is omitted.
[0010]
The bearing area of the connecting element advantageously has a semi-circular portion whose surface profile is matched to the loop to be supported and of as large a circular diameter as possible. This is because the fastening force caused by the strip is then transmitted to the at least one varistor element as a particularly uniformly received and uniformly acting contact force by the connecting element. The bearing area can be arranged in a projection or notch of the connecting element, which is formed as a shoulder or groove. In this case, it is particularly advantageous to form the groove. This is because the grooves can be formed without problems in the commonly used cylindrical connecting elements and at the same time guarantee a particularly reliable mounting of the corresponding loops.
[0011]
Due to the satisfactory mechanical stability of the active part, it is generally the case that two connecting areas are arranged opposite one another across the diameter, in each case one of two loops is mounted on each connecting element. It is enough. Additional stability is achieved by the use of three bearing areas, each bearing one of the three loops, offset azimuthally about 120 ° about the axis. Stability is further improved slightly by four or more bearing areas per connection member, but this requires additional manufacturing technology costs.
[0012]
The current path between the connecting elements is preferably provided with at least one current transmitting element that can be deformed in the event of a contact force. This ensures a particularly reliable contact connection between the two varistor elements or the connecting element and the varistor element or, if necessary, the pressure plate provided in the current path, and thus a good current transfer characteristic of the current transfer. It has proved to be particularly advantageous if the current-carrying element is formed as a disk, which is guided concentrically on the axis and has a groove formed on the end face of the disk. That is, the current transmission member configured in this manner seals the current transmission region in the active part so that the liquid insulating material does not enter when the casing of the surge arrester is cast.
[0013]
【Example】
BRIEF DESCRIPTION OF THE DRAWINGS FIG.
[0014]
The lightning arrester, which is shown in FIGS. 1 to 3 and has a substantially cylindrical symmetry, is preferably made of aluminum and has two connecting members 1 spaced apart from one another along the cylinder axis. , 2. The connecting member 1 has a fixing device (not shown) for an electric conductor. The groundable connecting member 2 is provided with an axially oriented screw hole 3 in which a pressure screw 4 is guided movably in the axial direction. Numeral 5 represents two loops of a band wound around, reinforced with glass fibers and embedded in a synthetic resin substrate. Both ends of these loops are guided by grooves 6 formed in the connecting members 1 and 2. The grooves 6 each form at the base of the groove a bearing area having a part of a semicircular surface profile, which is followed by two axially extending parts, respectively (FIG. 2).
[0015]
Between the connecting members 1 and 2, there is provided a cylindrical varistor element 7 made of a non-linear resistive material, for example based on a metal oxide such as ZnO. A disc-shaped pressure plate 8 made of aluminum is inserted into the notch of the connecting member 1. A current transmission member 10 is provided between the plate and the adjacent varistor element 7, between the adjacent varistor elements, and between another pressure plate plate 9 made of aluminum and another varistor element 7. Each is formed as a disk 10 with a groove guided concentrically on the axis and formed on two end faces of the disk. The disc 10 is advantageously formed from soft annealed aluminum.
[0016]
The connecting elements 1, 2 are partially surrounded by a varistor element 7, the pressure plates 8, 9 and the loop 5 by a cast casing 12, which is provided with a shield 11 and is made of an insulating material.
[0017]
In order to manufacture this lightning arrester, the connecting members 2, the pressing plates 9, the disks 10 and the varistor elements 7, the pressing plates 8 and the connecting members 1 are alternately stacked one after another in a mold. In this case, the grooves 6 of the two connecting members 1, 2 are positioned such that they are in line with one another (FIG. 1). Then, preferably, two prefabricated loops 5 each consisting of a wound strip of prepreg, each of which has been hardened after winding, are suspended in grooves 6 which are aligned with one another and a pressure screw 4 Is exerted on the pressure plate 9 and thus via the tensioned loop 5 on all remaining parts of the active part of the surge arrester.
[0018]
Instead of two pre-manufactured loops, two loops formed during the manufacture of the surge arrester can also be used. To form these loops, two strips, each of which is biased, are wound around two connecting members 1, 2 and rest in the bearing area of two lined grooves 6. Is done. In this case, the two connecting members 1, 2 are permanently fixed to one another on the basis of the formation of a contact force, so that a mechanically stable active part of the surge arrester to be manufactured is formed. Due to the satisfactory mechanical strength of the active part of the surge arrester, this fixation is generally already completely sufficient. Thus, if a strip having a satisfactory elasticity is used, as for example a strip already manufactured from glass fiber, the active part of the surge arrester simply consists of two connecting members 1,2 and at least one The varistor element 7 and the loop 5 may be formed.
[0019]
These strips are preferably prepregs, in particular based on glass fibers and epoxides. The prepreg has a good sticking action. The loop wound from the biased prepreg is therefore stable after winding without additional fixing devices and can then be cured even at elevated temperatures. Thus, in this case, a loop consisting of the wound strip and the hardened synthetic resin substrate embedding the strip, which also acts on the contact force of the active part and thus on the mechanical stability, is formed. Is done.
[0020]
In use of the disc 10, the clamping of the two connecting members 1, 2 simultaneously with the good contact connection of the individual parts present in the current path between the two connecting members, as well as the varistor element in the groove of the disc 10 Adhesion to the end faces of the connection member 7 and the connection members 1 and 2 and the pressure plates 8 and 9 provided as needed is also realized. Thus, if the active part of the lightning arrester is subsequently injection-molded with an insulating material, preferably based on silicone, the supply of liquid insulating material between the individual parts present in the current path is largely avoided. .
[0021]
As is evident from FIG. 4, the connecting member can also have two projections formed as shoulders 13 instead of two grooves. Protrusions of this kind can be easily formed on the connecting members 1, 2 and facilitate the supply of the loop 5.
[0022]
It is clear from FIGS. 5 and 6 that the connecting element can in some cases also have grooves or shoulders 13 which are each offset by 120 °. The incorporation of such connecting members 1, 2 can additionally increase the mechanical stability of the active part of the surge arrester when the contact force is predetermined.
[0023]
【The invention's effect】
The lightning arrester according to the invention has good mechanical and electrical properties in spite of its simple structure and can be manufactured particularly inexpensively.
[Brief description of the drawings]
FIG. 1 is a side view of a first embodiment of a lightning arrester according to the present invention, in which a portion of a casting casing on a viewer side is removed.
FIG. 2 is a front view of the lightning arrester of FIG. 1 taken along line II-II in the drawing.
FIG. 3 is a plan view of a connecting member of the lightning arrester according to the embodiment of the present invention shown in FIG. 1;
FIG. 4 is a plan view of a connection member of a lightning arrester according to a second embodiment of the present invention.
FIG. 5 is a plan view of a connection member of a lightning arrester according to a third embodiment of the present invention.
FIG. 6 is a plan view of a connection member of a lightning arrester according to a fourth embodiment of the present invention.
[Explanation of symbols]
1, 2 connection member, 3 screw hole, 4 pressure screw, 5 loop, 6 groove, 7 varistor element, 8, 9 pressure plate, 10 disk, 11 shield, 12 casting casing

Claims (10)

Two connecting members (1,2) spaced apart from one another along an axis and at least one cylindrical varistor element arranged between the two connecting members (1,2) (7) a device made of an insulating material for fastening the connection members (1, 2) and the at least one varistor element (7) under the formation of a contact force; and the connection members (1, 2). A lightning arrester having at least one varistor element (7) and a cast casing of insulating material at least partially surrounding the fixing device;
The fixing device has a pressure screw (4) and at least two fixing members, each acting independently of one another on the connecting member (1, 2) and each being configured as a loop (5). , The loop has two loop ends,
The connecting members (1, 2) each include a bearing area corresponding to the number of the loops (5), the bearing areas being distributed azimuthally uniformly around the axis , wherein: The bearing area is arranged on at least one projection of the two connecting members (1,2) formed as a shoulder (13) or in a notch formed as a groove (6),
The respective bearing areas of the first connecting member (1) of the two connecting members (1, 2) are axially aligned with the bearing areas of the second connecting member (2) of the two connecting members (1, 2). The two loop ends of the loop are supported in bearing areas that are aligned and are aligned with one another of the two connecting members (1, 2). A lightning arrester characterized by the following. 2. The lightning arrester according to claim 1, wherein each of the bearing areas for the loop has a part whose surface profile is semicircular. Wherein each of the two connecting members (1,2), surge arrester according to claim 1 or 2, wherein the two bearing regions are arranged to face in the relative diametrical direction to each other are provided. 4. A method according to claim 1, wherein each of said two connecting members is provided with three bearing areas which are angularly offset by about 120 DEG about said axis. 2. The lightning arrester according to claim 1. A lightning arrester according to any of the preceding claims, wherein at least one of the loops (5) comprises a wound strip. The lightning arrester according to claim 5 , wherein the wound strip is embedded in a synthetic resin base material. The lightning arrester according to claim 6 , wherein the synthetic resin base material is formed by curing a synthetic resin that can be cured before the loop (5) is placed on the bearing area. The lightning arrester according to claim 6 , wherein the synthetic resin base is formed by curing a synthetic resin that can be cured after the loop (5) is placed on the bearing area. A current path between said connecting members (1,2), deformable in the formation of contact force, of claims 1, at least one current carrying member is provided to 8 according to any one of Lightning arrester. 10. The surge arrester according to claim 9, wherein the current transmission member is formed as a disk (10) and has a groove guided concentrically on the axis and formed on the end face of the disk.

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